Apparatus for the control of highway crossing signals



April 8, 1941.

A. R. WHITEHORN Filed June 21, 1959 APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS INVENTOR.

ATTORNEY.

Patented Apr. 8, 1941 UNITED STATES APPARATUS FOR THE CONTROL OF HIGH WAY CROSSING SIGNALS Application June 21, 1939, Serial No. 280,259

12 Claims.

The present invention relates to apparatus for the control of highway crossing signals and particularly to such apparatus which is designed to operate the crossing signal at substantially the same time interval prior to the arrival of a train at the crossing regardless of the speed of the train. More specifically the invention comprises a signal-operating system for railroad-highway crossings in which the time interval required for the train to cross a short speed-gauging section causes the operation of one or more of a plurality of slow pick-up relays, having relatively short time delay intervals, there being a comparison time delay relay for each slow pick-up relay and the said comparison time delay relays functioning to determine the delay period which shall ensue after the train emerges from the short track section and before the signal is operated.

It is an object of the present invention to provide a new and improved train actuated railroadhighway grade crossing signal control system. It is another object of the invention to provide a crossing signal operating system for railroads in which the passage of a train through a relatively short track section causes, depending upon the time interval required, the actuation of one or more of a plurality of pick-up relays characterized by short time delay intervals which relays selectively control a plurality of comparison time delay relays having relatively great time interval characteristics. A still further object of the invention is to provide a train signal controlling system which effects the operation of the highway signal at approximately the same time interval before the arrival of the train at the crossing regardless of train speed and which includes a plurality of pick-up delay relays which are actuated sequentially and each of which is provided with a comparison time delay relay having a relatively long time delay characteristic and which is energized simultaneously with the fast pick-up relay but which is de-energized by the placing into operation of a subsequent relay, Still another object of the invention is to provide a signal operferred embodiment of the present invention is illustrated:

The single figure is a diagrammatic illustration of the electrical circuit comprising the present invention, the circuit being illustrated in the track-clear condition.

In the drawing a track formed of rails l, I is seen to cross a highway at V and to be divided into mutually insulated sections TU and UV. Section TU is a relativel short section which may be only two or three rails in length and is the measuring section. Section UV is of sufiicient length that the fastest train traveling on the track requires twenty seconds to traverse it in moving toward the highway and is the signal operating section. An example of the relative lengths can be taken as 176 feet for section TU and 3,520 feet for section UV. Each track section is provided with its own circuit comprising a battery 2 and the winding of a normally energized relay indicated by the reference character A in section TU and by the character B in section UV. The entering of a train in section TU moving in the direction of the highway causes the relay A to be shorted whereupon the front contact A3 thereof drops to the back contact A l and the operation of the signal control mechanism comprising the present invention begins. The purpose of the ap- I aratus is to control the flow of electric current to, and so the operation of, the signal S located at the highway. This signal is in the electrical circuit of front and back contacts Pi and P2 of rela P which is normally ener ized by a flow of current which is directly controlled by the apparatus comprising the present invention. Current is provided by a battery BAT as illustrated although any suitable source of current may be used.

or pick-up relays C, D, E and F are controlled by the relay A, and each of these pick-up relays opcrates, after being energized, with a time delay of approximately two-tenths of a second. Each pick-up relay includes a plurality of contacts which are indicated, for example in connection with rela 0, by character C coupled with a A series of relatively fast operating time delay thermal, it only being requisite that they be of the time delay genus. Each comparison relay is provided with its own movable and stationary contacts which bear the same reference letter and in addition thereto a numeral.

Each pick-up relay is provided with a comparison relay through which current passes upon the closing of contacts 1 and 8 in each case. If, for example, relay C is energized and picks up, electrical current immediately passes through the winding of comparison relay H, upon movable contact C'i closing on stationary contact C8. The comparison relays have different time interval characteristics, each successive relay in the series H, I, J and K, respectively, having an increased delay interval over the preceding relay.

The successive pick-up relays C, D, E and F are operated in series, first relay C being connected across the battery by the closure of contacts A3 and A l of relay A when that relay is shorted by the train entering section TU. The winding of relay C is connected across the battery by contacts A3 and A4, which are in series with contacts B3 and B4 on one side of the battery, and by the various contacts I and 2 of the comparison relays H, I, J and K to the other battery terminal. If a single comparison relay contact I is improperly positioned relay C cannot operate and current to relay P Will be cut oil upon the shorting of relay B, by the train entering section UV, and. the opening of contacts BI and B2. Such a condition gives the maximum warning period for the train will travel the entire length of section UV while the signal operates. If the train remains in section TU a sufficient length of time for relay C to pick up, the comparison relay contacts I and 2 being properly related, the closure of the contacts of relay C accomplishes a plurality of results. Through its contacts CI and C2 the winding of second pickup relay D is connected in parallel with relay C in its circuit with the battery. Through its contacts C3 and C4 its own stick winding CX is connected in series with contacts LI and L2 of relay L; its own contacts C5 and C6 place a short around contacts BI and B2 of relay B in the circuit of relay P so that the shorting of relay B cannot cause signal operation; and the closure of contacts and C8, respectively, places the check relay L in series with the battery whereupon the armature LI picks up and closes completing the stick circuit CX of relay C.

Assume that the train passing through the section TU takes just sufficient time that relay C only of the pick-up relays is energized. Upon entering section UV relay B is short-circuited and its back contacts BI and B3 drop from the stationary contacts B2 and B4. Contacts BI and B2 have been by-passed by the closure of contacts C and C6 of relay C so that current is not 7 cut off from control relay P. The opening of contacts B3 and 134, however, which are in series with contacts A3 and A4 has opened the circuit through the main winding of relay C and also the current flowing through contacts C2 and CI so that current no longer flows through the winding of relay D, thereby preventing subsequent operation of that element. If relay D has not been actuated by the time relay B opens it cannot be actuated. Relay C, however, does not return to its de-energized position upon the cutting off of current through its main winding for its stick circuit CX remains energized. This circuit includes the contacts C3, C4, and LI, L2 to one side of BAT and a direct connection thereto upon the other side. The current, which has been passing thru the winding of relay H since the closure of contacts 01, C8, continues to flow. After the passage of a time interval characteristic of relay H, movable contacts HI, H3 are actuated, HI moves from stationary contact H2 and H3 moves into contact with stationary contact H4. Contacts HI, H2 are in series with contacts I and 2 of each comparison relay and in the initial operation of relay C serves the function of checking the positions of all comparison relays which might later be called upon to control the signal delay period. Contacts I and 2 opening at this time accomplishes no result, the relay C main winding being de-energized by the shorting of relay B and the opening of contacts B3, B4. The closure of contacts H3 and H4, however, functions to place a short circuit across check relay L whereupon that relay opens, contact LI dropping from front contact L2. This opens the stick circuit thru CX, described above, and permits relay C to open. Thereupon contact C5 drops from contact C6 and the current to the signal-controlling relay P is cut off, the contacts of relay B having been opened previously.

Slow acting comparison time delay relay H is so calibrated that, for any train which traverses section TU at a speed such that pick-up relay C only is operated, and which means also that the train was not in section TU a suihcient length of time for subsequent pick-up relay D to operate, there will be a time delay before current is cut off controlling relay P which will enable the train to travel in section UV until it is approximately 20 seconds from the highway. This, of course, is not exact in every case but instead represents a very close approximation.

Assuming the train which travels through section TU to be a slower train it is not slow acting comparison time delay relay H which determines the delay during which the train travels in section UV before the actuation of the signal. Let it be supposed that the train is suificiently slow that relay C is energized, picks up, that contacts CI, C2 close and that current passes through the winding of second pick-up relay D for a sufficient period of time to actuate that relay. The contacts thereof are closed and the following result effected. The closure of contacts DI and D2 places the main winding of relay E in series so as to give that relay an opportunity to pick up should the train be in section TU a sufficient period of time. The closure of contacts D3 and D4 places the stick circuit DX of relay D in the circuit of the contact LI and L2 of check relay L and current passes therethrough. The movement of contact D'I from back contact D9 opens the circuit through comparison time delay relay H of the first unit and causes it to pass instead through front contact D8 into comparison time delay relay I of the second unit which is controlled by the pick-up relay D. Because relay D has had the opportunity to pick up it is indicated that the train which has selected it is a slower train than that which selected relay C in the first instance and, accordingly, it is indicated that the time delay interval for operation of relay I should be greater than that for relay H so as to give this slower train the opportunity to travel a greater distance in section UV before the signal is placed in operation so that the train can reach the crossing in approximately the same time interval thereafter as was required for the first train in the first instance.

In this second case, as in the first, at the end of the time delay interval required for the operation of the thermal relay I the contacts II and I3 operate and the closure of contacts I3 and I4 functions to place a short upon check relay L which in turn drops its movable contact Ll thereby opening the stick circuit through DX of relay D causing that relay to open and also the stick circuit CX of relay C causing that relay to open whereupon movable contact C5 drops from stationary contact C6, as in the first case, and opens the by-pass around the now open contacts Bl, B2 of relay B. As current to relay P is through contacts C5 and C6 which are now open, the relay is de-energized and signal operation ensues.

In the event that the train is a still slower train, then the subsequent pick-41p relays E and F are given opportunities, depending upon the speed of the train, to operate. In each instance the last pick-up relay to be actuated causes its comparison time delay relay to control the time delay period during which the train travels in section UV and before the signal is operated. In each instance the pick up of a subsequent pickup relay de-energizes the comparison delay relay of the previous unit by the opening of its contacts 'I and 9, thus leaving the comparison relay of the last unit alone to control the time delay period. It is clear that the main Winding of a subsequent pick-up relay and the winding of the delayed action comparison relay of the unit in which the pick-up relay has just operated are simultaneously energized. As the pick-up relays have delay periods which are relatively small as compared to that of the comparison relays the relationship is such that each energized comparison relay is de-energized by the operation of the pick-up relay of the later operated unit during the traversal of the timing section by the front of the train. Of course upon the train entering the operating section further energization of i pick-up relays is prevented and the operation of the comparison relay last energized controls signal operation.

Each pick-up relay with its contacts and comparison relay may be considered as a unit and these units are seen to be very similar. Of the contacts of the pick-up relays the following points in common are noted: the closing of contacts I, 2 function to close an electric circuit thru the main winding of the subsequent pick-up relay; the closing of contacts 3, 4 completes the circuit thru the stick winding; in relay C the closing of contacts 5, 6 places a short around contacts I, 2 of track relay B in the circuit of control relay P and until opened the signal cannot operate; the closing of contacts I, 8 causes current to pass thru the Winding of the comparison time delay relay of the unit; and the opening of contacts I, 9 in each unit subsequent to C causes the opening of the circuit thru the comparison relay of the previous unit. The contacts of each comparison time delay relay of each unit performs the following functions: contacts l, 2 being in series with contacts I, 2 of every other comparison relay functions to check the proper positioning thereof before current can flow thru any pick-up relay mainwinding; contacts 3, 4 when closed by the final operation of the selected comparison relay places a short upon the winding of check relay L which then drops its back contact l, thereby opening the various stick circuits and resulting in the opening of relay C and the separation of contacts C5, C6 whereupon relay P is de-energized and the signal operates.

Obviously the apparatus constructed in accordance with the present invention may be as selective as the designer desires, the number of and the time interval differentials existing between the relays C, D, E, F, etc. being the controlling factors. For purposes of economy differentials between those selected relays will be so chosen as to give a desirable range to conform to the op erating speeds of the train traversing the track, and they will be sufficient in number to insure the desired particularity of operation.

The use of the relatively fast pick-up relays C, D, E and F, etc. makes possible the use of a short speed-determining section TU and the placing of the slow comparison time delay relays in operation immediately is a characteristic of this type of connection which is desirable, as are the multiple safety checks.

In one circumstance, that in which the train traverses the section TU so fast that even relay C cannot pick up, the signal will be placed in operation immediately the train enters section UV, and upon the shorting of relay B. The dropping of contacts Bi and B3 before the by-pass contacts C5 and Ct have closed causes the circuit to the signal-controlling relay P to be opened whereupon the contacts Pi and P2 close and cur-- rent flows directly to the signal. There is really provided, ther fore, a selection of speed controls equal to the number of pick-up relays used plus one.

Relay L, in addition to functioning as a front contact to hold up the stick circuit, also serves as a check upon the comparison time delay relays, and if for any reason there is an open circuit preventing the flow of current to a time delay relay the relay L will fail to pick up to complete the stick circuit. It therefore serves as a check on the thermal relays heating.

As is common practice the right hand winding Q of relay P is also intended to control the operation of contacts Pi and P2 in response to controls operated in response to trains approaching the highway from the opposite direction.

I claim:

1. In combination, a stretch of railway track intersected by a highway, said tr ack being divided upon one side of the highway into a timing section and a signal-operating section insulated therefrom, a normally-energized track relay in each of said sections, a signal at the intersection of the track and highway, and means to effect the operation of said signal prior to the arrival of a train at the intersection comprising a plurality of relay units arra lged for sequential operation and each including a slow pick-up relay and a time delay comparison relay, the Winding of each pick up relay being in a circuit serially iiieluding contacts of said track relays and, excepting only the first pick-up relay, a contact of a preceding pick-up relay to effect sequential operation during the time a train is in the timing section and before it enters the signal-operat ing section whereby the number of pick-up relays operated depends upon the time required for a train to "travel the timing section, means to energize each comparison relay upon the selection of the pick-up relay of the same unit, means to deenergiae the comparison relay of the preceding unit upon the selection of the pick-up unit of the next subsequent un-it, the time delay characteristics of the comparison relays progressively increasing in the series, and means to effect signal operation upon the operation of the comparison relay of the unit including the pick-up relay last energized.

2. In combination, a stretch of railway track intersected by a highway, said track being divided upon one side of the highway into a timing section and a signal-operating section insulated therefrom, a normally-energized track relay in each of said sections, a signal at the intersection of the track and highway, and means to efiect the operation of said signal at a substantially constant time interval prior to the arrival of a train at the intersection regardless of train speed comprising a plurality of normally de-energized slow pick-up relays each including a plurality of contacts and a corresponding number of normally deenergized comparison time-delay relays having progressively increasing time delay characteristics and each including a contact, means includ ing the track relay in the timing section and a contact of each of said pick-up relays excepting only the last to eiiect sequential operation of said pick-up relays while a train travels the timing section only, means to energize sequentially said comparison relays upon the sequential operation of said pick-up relays, said comparison relays each being controlled by an associated pick-up relay, means to de-en-ergize previously energized comparison relays upon the energization of a subsequent comparison relay, means to prevent the subsequent energization of pick-up relays upon a train entering said signal-operating track sec tion, and means to enact signal operation upon the operation of the last energized comparison relay.

3. In combination, a stretch of railway track intersected by a highway, said track being divided upon one side of the highway into a timing section and a signal-operating section insulated therefrom, a normally-energized track relay in each of said sections, a signal at the intersection of the track and highway, and means to effect the operation of said signal at substantially a constant time interval prior to the arrival of a train at the intersection comp-rising a plurality of normally deenergized pick-up relays each including a plurality of contacts and a corresponding number which have progressively increasing time delay characteristics and each of which include a plurality of contacts, means to energize said pick-up relays sequentially to a number depending upon and during the time required for the front end of a train to pass through said timing section said means including a contact of each pick-up relay in series with the winding of the pick-up relay next to be operated, a contact of each of said track relays, and a checking contact of each of said comparison relays, means to energize said comparison relays in a predetermined sequence upon the operation of said pickup relays including a contact of an associate pick-up relay for each comparison relay, means to de-energize the previously energized comparison relay upon the subsequent actuation of a pick-up relay comprising a contact controlled by that pick-up relay, and means to effect signal operation upon the operation of the last energized comparison relay. 1

4. In combination, a stretch of railway track intersected by a highway, a signal at the intersection said track being divided upon one side of the highway into a timing section and a signaloperating section insulated therefrom, track relays in said sections, a plurality of pick-up relays and a corresponding number of comparison time delay relays the time delay characteristics of which progressively increase, a circuit for the first pick-up relay including a contact of each of said track relays, a contact actuated by each pick-up relay to connect a subsequent pick-up relay in parallel therewith, a contact actuated by said first pick-up relay to energize a first cornparison relay, a contact controlled by said pickup relays excepting the first to ole-energize the comparison relay energized by the preceding pickup relay, a contact controlled by each pick-up relay subsequent to the first to energize an associate comparison relay, the energization of successive pick-up relays continuing with a, train traversing said timing section but being inter- .rupted by the operation of the contact of the track relay in the signal operating section upon the train entering that section, and means to effect signal operation upon the operation of the last energized comparison relay.

5. In combination, a stretch of railway track intersected by a highway, a signal at the intersection said track being divided upon one side of the highway into a timing section and a signaloperating section insulated therefrom, track relays in said sections, a plurality of successively operated slow pick-up relays and an associate comparison time delay relay for each, the time delay characteristics of said comparison relays increasing in the success-ion of said pick-up relays a circuit for the first pick-up relay including contacts of said track relays, a contact actuated by each pick-up relay to connect a subsequent pick-up relay in parallel therewith, a contact actuated by said first pick-up relay to energize its associate comparison relay, stick circuits for said pick-up relays including a contact of each relay to connect it in parallel with preceding pick-up relays, contacts controlled by each subsequent pick-up relay to de-energize the comparison relay energized by the preceding pick-up relay and to energize its own associate comparison relay, energization of successive pick-up relays continuing with a train in the timing section and energization of further relays being prevented upon the operation of the contact of the track relay in the operating section when a train enters that section, a contact in each comparison relay to control the stick circuits of said pick-up relays and to efiect the de-energiza tion thereof upon the actuation of the last energized comparison relay, and normally-energized means to effect a flow of current to the signal upon the de-energization of the stick circuit of the first relay and its return to initial position.

6. In combination, a stretch of railway track divided into measuring and operating sections, the latter of which is intersected by a highway, a track circuit for each of said sections includ ing a track relay, a highway crossing signal at the intersection, a plurality of relay units each comprising a pick-up relay and a time delay relay, means set into operation by the track relay of the measuring section for sequentially energizing the pick-up relays oi said units to a number determined by the time said measuring section is occupied by a train prior to its entry into said operating section, means to energize the time delay relay of each unit upon the energization of the pick-up relay of that unit, means set into operation by the track relay of the operating section upon the entry of a train into that section to render inoperative unenergized pick-up relays, and means effective to start the operation of said signal upon the operation of the last-energized time delay relay, characterized in that the time delay characteristics of said comparison relays are difierent and are such that in each instance under the influence of the last energized relay the signal is placed in operation for a desired warning period prior to the arrival of the train at the intersection.

7. In combination, a stretch of railway track divided into measuring and operating sections, the latter of which i intersected by a highway, a track circuit for each of said sections includ ing a track relay, a highway crossing signal at the intersection, a plurality of relay units each comprising a pick-up relay and a time delay relay, means set into operation by the track relay of the measuring section for sequentially energizing the pick-up relays of said units to a number determined by the time said measuring section is occupied by a train prior to its entry into said operating section, means to energize the time delay relay of each unit upon the energizatio-n. of the pick-up relay of that unit, means to de-energize the last previously energized time delay relay upon the operation of the pick-up relay of the next succeeding relay unit, means set into operation by the track relay of the operating section upon the entry of a train into that section to render inoperative unenergized pick-up relays, I

and means eiiective to start the operation of said signal upon the operation of the last-energized time delay relay, characterized in that the time delay characteristics of said comparison relays are different and are such that in each instance I divided into a relatively short measuring section and relatively long operating section, the latter of which is intersected by a highway, a track circuit for each of said sections including a track relay, a highway signal at the intersection, and means to effect operation of said signal at sul stantially a constant time interval prior to the arrival of a train at the intersection, comprising a plurality of sequentially operable units each having a time delay relay the time delay periods of which increase through the sequence, means set into operation by said measuring section track relay and rendered inoperative by said operating track relay to energize said units including said time delay relays sequentially upon the passage i of the front of a train through said measuring section, and means to operate said signal with said train in said operating section upon the operation of said time delay relay of the last energized unit.

9. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located adjacent the intersection, speed measuring means including a plurality of relays selectively controlled by a train approaching a fixed point in the rear of the intersection to measure the speed of the train, time measuring means including a time delay relay for each of said first mentioned relays, said time delay relays having different time delay characteristics, means governed by said first mentioned relays to energize a particular time delay relay upon the operation of each of said first mentioned relays, and circuit means governed by said time delay relays for setting the signal into operation when the selected time delay relay has operated, the time delay characteristic of each time delay relay being such that the signal is placed into operation for the desired warning period prior to the arrival of the train at the intersection.

10. In a control system to provide a constant warning period irrespective of train speed for a signal at the intersection of a highway and a stretch of railway track, means including a plurality of sequentially operable pick-up relays adapted to be controlled by a train approaching the highway and the number of which are operated being determined by the length of time of its travel through a short timing sect-ion, a plurality of sequentially operabl time delay relays having difierenlt time delay characteristics and each of which is energized at the time of operation of an associate pick-up relay, and means controlled by said time delay relays and adapted to control the operation of a signal circuit .at a desired time interval prior to the arrival of a train at the intersection.

11. In combination, a stretch of railway track divided into a relatively short measuring section and relatively long operating section, the latter of which is intersected by a highway, a highway signal at the intersection, and means to effect operation of said signal at substantially a constant time interval prior to the arrival of a train at the intersection irrespective of train speed comprising a plurality of time delay relays of differing delay periods, means controlled by the passage of the front end of a train through said measuring section to energize said time delay relay-s sequentially and singly and in the order of increasing time delay periods, means to prevent further energization of said relays upon the front of said train entering said operating section, and means to effect operation of said signal upon the operation of the time delay relay energized last.

i1 2. In combination, a stretch of railway track divided into a relatively short measuring section and relatively long operating section, the latter of which is intersected by a highway, a highway signal at the intersection, and means to efiect operation of said signal at substantially a constant time interval prior to the arrival ed a train at the intersection irrespective of train speed comprising a track circuit for each of said sections each including a track relay, a plurality of s quentially operable pick-up relays having windings in a circuit serially including contacts of said track relays and, excepting only the first pick-up relay, a contact of a preceding pick-up relay, stick windings for said pick-up relays connected in parallel to an energizing source and each including a controlled contact, said pick-up relays being sequentially energized during the passage of the front of a train through said measuring section and held in the operated position by the action of the stick windings, the number of pick-up relays energized depending on the time required for said passage, a plurality of sequentially operable time delay relays having progressively increasing time delay characteristics and windings in circuits including contacts of said pick-up rclays whereby the operation of each pick-up relay effects the energization of an associate time delay relay and, excepting only the first operated pickup relay, the :de-energization of a previously energized time delay relay, the sequential energize tion of said pick-up relays being terminated by the operation of the contact of the operating-section-track relay, and means to effect signal operation upon the operation of the last energized time delay relay.

ARTHUR H. WI-IlTE l-IORN. 

